In medical and dental establishments, because of environmental problems and the cost and difficulty of burning and dumping of medical waste, there is a growing tendency to return to reusable products. For example medical and dental instruments after use are frequently returned in a container to a washing or sterilising facility where the instruments are decontaminated. The instruments can then be safely handled without risk from infections such as HIV and Hepatitis caused by inadvertent cutting or puncturing of the person handling a contaminated instrument. The instrument can be cleaned and serviced as necessary and sterilisation in an autoclave follows, usually with porous filter medium surrounding the tray or other container holding the instruments. The instruments while remaining protected by the porous wrapping are then stored and subsequently returned to the surgery for reuse by the dentist or doctor.
Trays made of stainless steel and synthetic materials are known for holding dental and medical instruments for sterilisation in an autoclave. Such stainless steel trays have a base made of a sheet of flat stainless steel material which has an array of cylindrical holes drilled through the base to allow steam in the autoclave to pass through the base. However such stainless and synthetic steel trays are expensive and/or may not allow steam or washing liquid to reach all parts of the instruments resting on them.
Australian Patent Specification No. AU-24539/88 discloses an autoclave container in the form of a tray made of a plastics material, the tray having a base with perforations defined by walls, the walls progressively widening from a top point to a flat bottom surface of the base. The flat bottom surface enables a substantial amount of the heat stored within the plastics material after the tray has been an autoclave to be yielded up through the flat base surface and thereby help evaporate any moisture, such as condensation, particularly within the filter material placed around the tray when in the autoclave. However the tray in this patent specification would not be particularly effective in a washer where water jets are directed upwardly against the base of the tray, since the large flat bottom surface area would deflect much of the water downwardly rather than allowing the water to pass upwardly through the perforations to reach the instruments in the tray.
A type of closed autoclave vessel frequently used in hospitals for holding instruments to be sterilised in an autoclave has a square bottom of about 40 cm width and which has a perforated central opening, e.g. having a diameter of about 10 cm. The circular central opening in use is covered by a permeable filter material. The lid of the vessel is similarly constructed, having a 10 cm diameter circular perforated opening in the centre of the lid covered in use by a permeable filter. Inside the closed vessel there can be a tray which is perforated and which supports the instruments to be sterilised. Steam flows through the upper circular opening in the lid to reach the interior of the vessel and passes out through the lower central perforated opening. The flow of steam through such a vessel tends to be greatest in the central region of the space enclosed within the vessel, this effect being the result of the steam flowing through a path of least resistance. Hence it is possible that the outer sides and particularly the corners of the vessel may be inadequately heated to effectively sterilise the instruments at the edges or in the corners of the vessel.
Australian Patent Specification No. AU-24396/95 (Patent No. 682770) discloses a container component for enabling cleaning of articles by fluid flow therethrough, the component having a base with perforations defined by intersecting perforation walls. Each of the walls in vertical cross section has a narrow top, widens in a downwards direction to a maximum width, and then narrows again to a narrow bottom. The preferred cross sectional shape of the perforation walls is elliptical with the major axis of the ellipse being upright. This container component, and also the tray disclosed in AU-24539/88, has many locations such as corners or crevices where small quantities of blood, debris, or other deposits or contaminants can be lodged and can be difficult to completely remove during the cleaning process. Such deposits can later contaminate instruments or other articles stored within the container component, or can dislodge in a surgery or other environment where all possible sources of contamination are desirably excluded. Even if the deposits are sterilised during the cleaning operation which the container component and instruments or articles carried thereby undergo, nevertheless the deposits are an undesirable potential source of particulate contamination in surgery, dental procedure, etc.
It is an object of the present invention in a first aspect to provide a container component for enabling fluid flow therethrough for effective cleaning of contents of the container with reduced risk of contaminants or deposits lodging or remaining in the container component.
It is a preferred object of the present invention to provide a container component suitable for placement within a washer in which washing liquid is directed upwardly and/or downwardly so as to pass through the container component thereby washing articles in the container and removing any contaminants or deposits in or on the container component.
It is a further preferred object of the present invention to provide a container component suitable for use in an autoclave and enabling steam to flow through the container component for effective sterilisation of articles in the container and removing any contaminants or deposits in or on the container component.
It is an object of the present invention in a second aspect to provide a method for cleaning or sterilising articles located within a container having a container component enabling a fluid flow therethrough with reduced risk of contaminants or deposits lodging or remaining in or on the container component.